There are no such things as coin flips

byRichard Li|May 6, 2014at11:50 PM

After game 4 of the Houston Rockets vs Portland Trailblazers series, Daryl Morey remarked that he was not concerned because his team had essentially lost three out of four coin flips. Perhaps this was a general manager putting on a good face. Or perhaps he truly believed that fortune had simply not favored his team. As a data egghead, I tend not to believe in fortune or happenstance and vehemently disagree with Morey’s summation of how the games reached their conclusions.

Yes, the games were close. However, the games were not necessarily close for their entire durations. Their final scores disguise the fact that the Rockets held comfortable leads in most of the games, only to cough up those leads late in the games. While it might be easy, or even comfortable, to think that random bounces of the ball are responsible for these lead switches, looking at the data suggests that there is more going on. Take a look at this chart.

Houston Rockets performance by quarter

The Houston Rockets performance for the entire season is shown from quarter to quarter, both on offense and defense (remember, lower numbers are better for defense). The dotted grey line shows the NBA average for comparison (since offensive and defensive ratings are exactly the same for the NBA as a whole, there is only one line that represents both.

Unsurprisingly, the Rockets start strongly and finish weakly on both sides of the ball. During the first quarter, the Rockets have an offensive rating over 110 points per 100 possessions and a defensive rating of 100. Those numbers then diminish during the second. Coming out halftime, the Rockets have renewed offensive success but struggle even more defensively. In the fourth quarter, the Rockets net rating, which was over +10 in the first quarter, is dead even. In overtime, their net rating is negative, with both offensive and defensive ratings worse than the league average.

Starting out strongly, ending with a whimper, especially in overtime. Does that sound familiar? It should, because that’s pretty much how every game in the Portland series played itself out. How these games transpired is not just random noise. They’re part of a larger signal that has been developed throughout the course of the entire season.

This tragic trend fits neatly into the most popular criticisms that we’ve discussed all season, ones that manifested themselves most glaringly in the playoffs. For starters, it’s clear that the Rockets are awful at making in-game adjustments, while their opponents are much better at it. By the end of the game, the Rockets’ opponents have figured out how to score on them, and stop them from scoring. Meanwhile, the Rockets don’t seem to have much of a counter punch.

The data also suggests that the Rockets could be more tired than their opponents. They start with a bang, wane a little in the second quarter, regain some strength during halftime, and then fade into oblivion. I’ve been critical all season about the Rockets’ usage of their bench, which was the 5th most productive but second to last in minutes played. I have to believe that fatigue is playing a role in the Rockets’ diminished performance late in games.

Finally, our old nemeses heroball and crunch time strategy need to be mentioned. I’m just completely flummoxed that the team most concerned with efficiency relies on the two least efficient plays, isolation and post-ups. During crunch time, it’s even worse. It’s like whatever “strategy” the Rockets had to begin with (and gave them a net rating of +10 in the first quarter) is abandoned because cliches about the best player taking whatever shot he can magically outweigh data in the final five minutes of games.

Pessimistic summary: The Rockets’ advantage in individual talent diminishes as the opposition successfully adjusts over the course of a game and the Rockets fail to. Unsure what to do next, the Rockets (OK, McHale, I’ll say it) throw their tiny playbook drawn on a 3″ x 5″ spiral notepad out the window and just give the ball to their two best players and expect good things to happen.

When good things inevitably don’t happen, it’s not because of a bad coin flip.

No related posts.

About the author: Richard Li is an independent researcher and consultant. He likes numbers and pictures.